WSU Extension

Hortsense

Ornamental Plum
 
Disease
Armillaria root rot 
Brown rot 
Crown gall 
Cytospora canker 
Plum pockets 
Shothole (Coryneum blight) 
Silver leaf 
Viruses 
Insect
Hop aphid 
Leaf curl plum aphid 
Peachtree borer 
Pear slug 
Scales 



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Caption: Brown rot blossom infection
Photo by: R.S. Byther
  
Ornamental Plum : Brown rot
(revision date: 4/28/2014)


Biology
Brown rot is a fungal disease which initially infects the flowers. The petals turn light brown, develop water-soaked spots and may have tan or grayish areas of fungal spores. Infected flowers often remain attached to the plant, spreading the disease to small twigs and branches. Infected twigs and branches are often observed in the summer as flagged, dead leaves and twigs. Infected branches develop cankers which may produce gumming (leaking sap) or may girdle and kill the branch. Most brown rot cankers develop with a dead twig at the center where the initial branch infection occurred. Fruit can also be infected, dry out, and hang in the tree. Tan or gray fungal spores can also be found on infected blossoms, fruit, or twig cankers. Ornamental and fruiting stone fruit trees are affected.
Management Options


Non-Chemical Management
  • Avoid overhead watering.
  • Avoid wounding trees.
  • Remove and destroy all infected twigs and branches during the summer, making pruning cuts well below infected tissues.
  • Clean up and destroy fallen flowers and other debris beneath trees.
Select non-chemical management options as your first choice!

Chemical Management

Apply fungicides during bloom period at full bloom and petal fall to control the blossom blight phase. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bonide Fung-onil Multi-Purpose Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 60063-9-4
  • Bonide Liquid Copper Fungicide Conc/Organic Gardening
    Active ingredient: copper octanoate  |  EPA reg no: 67702-2-4
  • This list may not include all products registered for this use.
Images

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Caption: Brown rot blossom infection
Photo by: R.S. Byther
Caption: Plum brown rot
Photo by: R.S. Byther